西菲律宾海盆表层沉积硅藻分布特征

CHARACTERISTICS OF DIATOM DISTRIBUTION IN THE SURFACE SEDIMENTS OF THE WESTERN PHILIPPINE BASIN

本文对西菲律宾海盆186个表层沉积硅藻样品进行分析,共鉴定出硅藻68个种和变种,隶属于26个属。西菲律宾海盆硅藻总平均丰度为1 111.5粒/g。硅藻属种主要以外洋暖水种和广温种为主,其中Azpeitia nodulifera的百分含量最高,其次是Hemidiscus cuneiformis,Coscinodiscus africanus,Thalasiosira excentrica和Nitzschia marina,以上5种硅藻占所有硅藻百分含量的88%以上。西菲律宾海盆大部分站位热带远洋种含量均高于20%,这与现今黑潮暖流流经该区相吻合。通过主成分分析,该海域表层沉积硅藻可分划为3个区域。此外,整个菲律宾海盆大部分海域都分布有Ethmodiscus rex,但西菲律宾海盆的分布范围更广。

Diatoms were analyzed for the surface sediment of the western Philippine Basin, including 68 species（inclu- ding varieties） and 26 genera. The total average abundance are 1 111.5 cells/g. The dominant groups are oceanic warm-water species and eurythermal species. It was found that the relative percentage of Azpeitia nodulifera is the highest, and that of Hemidiscus cunei f ormis , Coscinodiscus a f ricanus , Thalassiosira excentrica and Nitzschia mari- na takes the second place. The five species take about 88% of all diatom species＇ relative percentage. In most sta- tions, tropical pelagic species have higher content more than 20%, which is in consistent with the present Kuroshio Current flows in the area. On the western Philippine Basin, principal component analysis suggests that the diatoms can be divided into three Sub-regions. In addition, Ethmodiscus has a relatively wide distribution in the western Phil- ippine Basin.